1. Field of the Invention
The present invention relates to a method for joining plates and a plate joining structure, and more particularly, to a method for joining plates using plastic deformation of plates and a plate joining structure.
2. Discussion of the Background
FIG. 1 is a perspective view of a display module that may be employed in a plasma display device.
Referring to FIG. 1, the display module includes a display panel 50, a plurality of driving circuit boards 40 having circuits for driving the display panel 50, and a chassis 10 that supports the display panel 50 and the driving circuit boards 40.
The display panel 50 includes a front substrate 51 and a rear substrate 52 that are joined together, and it is coupled with the driving circuit boards 40 by connection cables 20.
The chassis 10 supports the display panel 50, which is mounted on the chassis' front surface, and the driving circuit boards 40, which are mounted on the chassis' rear surface. However, the chassis 10 is preferably formed as thin as possible to minimize the plasma display device's overall weight. Therefore, as FIG. 1 shows, a reinforcing member 12 may be coupled with a thin chassis base 11 to reinforce the chassis base 11, thereby assisting with supporting the display panel 50 and the driving circuit boards 40. Not only does the chassis base 11 support the display panel 50 and the driving circuit boards 40, but it also acts as a ground for circuits coupled with the display panel 50 and the driving circuit boards 40. Further, the chassis base 11 dissipates heat generated from the display panel 50 during operation.
The connection cables 20 comprise tape carrier packages (TCP). In the connection cables 20, a plurality of cables extend in a length direction of the connection cable 20, and at least a portion of the connection cables 20 is coupled with an integrated circuit chip 21 that is mounted on the connection cables 20. The integrated circuit chip 21 is fixed on the reinforcing member 12, and a cover plate 60, which protects the connection cables 20 and the integrated circuit chip 21, is coupled with the reinforcing member 12. The cover plate 60 may be coupled with the reinforcing member 12 using fasteners, such as screws 61.
FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, and FIG. 3A, FIG. 3B, and FIG. 3C are cross-sectional views showing a method of forming the plate joining structure.
Referring to FIG. 2, FIG. 3A, FIG. 3B, and FIG. 3C, the chassis base 11 and the reinforcing member 12 are joined together by plastic deformation at portion where they overlap. That is, after overlapping the chassis base 11 and the reinforcing member 12, plastic deformation is generated, using a tool 93, 94 having a predetermined shape, on an overlapped portion of the two plates by applying a high compression force from both sides of the plates. In the joining structure 80, the joining force is generated from a shaped-joining formed by contacting a protruded portion 84 of the lower plate 92 with a depressed portion 83 of the upper plate 91. That is, the shape of the protruded portion 84 of the lower plate 92 is formed corresponding to the shape of the depressed portion 83 of the upper plate 91, and the protruded portion 84 and the depressed portion 83 interfere with each other's relative motion.
The overall weight of the display panel 50 and the driving circuit boards 40 may vary according to the size of the modules, but, in general, it is about 30-100 kg.
However, in a conventional joined structure, it may be difficult to achieve a desired level of plastic deformation of the chassis base 11 and the reinforcing member 12 due to the thickness of the reinforcing member 12, which requires greater strength than that of the chassis base 11. Accordingly, the joining force of the joined portion may not be strong enough to withstand the weight of the driving circuit boards and the display panel. Consequently, the joined portion may become deformed. Therefore, there is a need to develop an improved plate joining structure and a method for joining plates.